Sanding pad



0d. 6, 1964 'E, HALL 3,151,425

SANDING PAD Filed July 24, 1962 2 Sheets-Sheet 1 United States Patent 3,151,425 SANDING PAD Emery L. Hall, Hinsdale, Ill., assignor to Ski! Corporation, Chicago, 111., a corporation of Delaware Filed .lnly 24, E62, Ser. No. 212,025 7 (Claims. (Cl. 51-379) The present invention relates to sanding pads and, more particularly, to a new and novel rotatable sanding pad for supporting an abrasive disc.

It is an important object of the present invention to provide a new and improved sanding pad for supporting an abrasive disc including a generally circular pad member having a generally concave slightly conical undersurface against which the abrasive disc is retained, which undersurface is provided with a multiplicity of radially extending flexible saw-tooth ribs which are inclined circumferentially in the same direction that the sanding pad is to be rotated whereby to aid in preventing slippage of the abrasive disc relative thereto.

A further object of the present invention is to provide a new and improved sanding pad of the character described having a circular pad member formed of hard rubber-like material wherein the thickness of the pad member decreases toward the outer edge of the pad member and wherein radial grooves defining the radial saw-tooth ribs on the undersurface thereof increase in depth and width toward the outer edge of the pad member, whereby to provide greater flexibility at the outer portion of the sanding pad where the sanding pressure is greatest.

Another important object of the present invention is to provide a new and improved sanding pad of the character described wherein the circular pad member is molded about a centrally bored fitting which is connectable at its upper end to a rotatable drive member and which has a pair of diametrically opposite longitudinally spaced lugs projecting radially inwardly of the lower end of the central bore therein, and having an abrasive disc retainer characterized by an upper threaded end portion which is rotatably insertable into the lower end of the fitting bore for retaining engagement with the pair of lugs therein and by a radial flange portion at its lower end for retaining an abrasive disc against the undersurface of the pad member.

Certain other objects of the invention will, in part, be obvious, and will in part appear hereinafter.

For a more complete understanding of the nature and scope of the invention reference may now be had to the accompanying drawings where-in:

FIG. 1 is an exploded side elevational View of a sanding pad embodying the invention including a circular pad member, an abrasive disc, and a disc retainer;

FIG. 2 is a top plan view of the pad member of FIG. 1;

FIG. 3 is a vertical section taken generally on the line 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary bottom plan view looking toward the underside of the pad member of FIGS. 1, 2 and 3;

FIG. 5 is a vertical section taken generally on the line 5-5 of FIG. 4; and

FIG. 6 is a vertical section taken generally on the line 6 of FIG. 4.

As illustrated in FIG. 1, a generally circular sanding pad 16 embodying the invention includes a disc retainer 11 for retaining a circular abrasive disc 12 against the underside thereof. The sanding pad 10, as best illustrated in FIG. 3, further includes a centrally bored metallic fitting 13 having an outwardly extending radial flange portion 14 and a circular pad member 15 formed of hard rubber-like material which is molded about the lower the pad and the abrasive disc.

3,l5 l,425 Patented Get. 6, 1964 end of the fitting 13 and the flange portion 14 thereof. As illustrated, the pad member 15 is molded on the fitting 13 in a manner such that no portion thereof extends over the lower end of a central through bore 16 in the fitting 13. The upper portion of the central bore 16 in the fitting 13 is provided with an internal thread 17 for rotatably mounting the sanding pad 10 on a rotatable driving member of a known type. A lower enlarged diameter portion 18 of the central bore 16 in the fitting 13 is provided with a pair of diametrically opposite inwardly projecting lugs 19 which are longitudinally spaced apart a predetermined distance for a purpose which will be described hereinafter.

The upper surface of the pad member 15 is inclined downwardly at a slight angle to the horizontal to define a conical upper surface 20 with the lower surface thereof being inclined downwardly at a lesser angle whereby the upper and lower surfaces of the pad member 15 converge slightly so as .to define a pad member 15 having a generally concave slightly conical undersurface 21 with the body portion of the pad member 15 having a thickness at its outer peripheral edge 22 which is less than the thickness thereof immediately adjacent the fitting 30.

As best illustrated in FIG. 4, the undersurface 2.1 of the pad member 15 is provided with a multiplicity of radially extending generally V-shaped grooves 23, the inner ends of which terminate in spaced relationship to the inner peripheral edge of the pad member 15 and the outer ends of which intersect the outer peripheral edge 22 of the pad member 15. A multiplicity of radially extending flexible saw-tooth ribs 2-4 are defined by and between the grooves 23 with the ribs 24 being inclined circumferentially in the same direction that the sanding pad 10 is to be rotated whereby to aid in preventing slippage of an abrasive disc 12 retained against the undersurface 21 of the pad member 15 relative thereto during a sanding operation. As best illustrated in FIGS. 5 and 6, each rib 24 is defined by a straight side wall 24a disposed in a plane which passes through the longitudinal axis of the fitting 13 and by an inclined side wall 24b, whereby to provide the saw-tooth effect.

Pad 15 is rotated in a clockwise direction, as viewed in FIG. 2, so that walls 24a, which are normal to the underside of the pad, are advanced forwardly of associated inclined walls 24!). The sharp radial edges defined by the juncture of walls 24a, 24b present a small surface area in contact with the back of the abrasive disc'thereby developing an increased pressure between these edges and the abrasive disc for a given amount of force between This causes these sharp radial edges defined by walls 24a, 24b to dig or bite into the back of the abrasive disc thereby to prevent slippage between the latter and the pad. Also, the saw tooth ribs, because of their reduced cross sectional area, flex rather readily to maintain the biting engagement bet veen the sharp edges of the ribs and the back of the abrasive disc during bending of the pad and abrasive disc as, for example, when objects with irregular contours are being sanded.

As is best illustrated in FIGS. 4, 5 and 6, the grooves 23 increase progressively in depth and width toward the outer peripheral edge 22 of the pad member 15 whereby to provide greater rib flexibility at the outer portion of the pad member 15 where the sanding pressure is greatest. The lesser thickness of the pad member 15 at its outer edge 22 also aids in increasing the flexibility thereof.

The disc retainer 11- (FIG. 1) is provided at its upper end with an external thread formation 26 which may be squared in configuration. The lower end of the re tainer 11 is provided with an outwardly projecting radial flange portion 23 which is characterized by a conical upper surface 30 which is generally complementary to the non-grooved inner portion of the generally concave conical undersurface 21 of the pad member 15.

With a centrally bored abrasive disc 12 disposed against the undersurface 21 of the pad member 15, the retainer 11 is rotatably inserted through the abrasive disc 12 and into the lower end of the central bore 16 in the fitting 13 whereby to interengage the external thread 26 thereon with the pair of diametrically opposite longitudinally spaced lugs 19 which extend inwardly of the lower por tion 18 ot the fitting bore 16 with the flange portion 28 of the retainer 11 serving to retain the abrasive disc 12 tightly against the undersurr'ace 21 of the pad member 15. When it is necessary to replace a used abrasive disc with a new one, the disc retainer 11 is merely rotated in the opposite direction to disengage the thread 26 thereof from the pair of lugs 19.

The lug 19 and thread 26 arrangement for releasably interconnecting the disc retainer 11 and the pad member fitting 13 provides a number of novel advantages over the more commonly used mating internal and external thread connections. For instance, there is substantially less wearing of the thread 26 as a result of abrasive action thereon than if a mating male and female thread arrangement were utilized. The lug arrangement 19 in the central bore 16 of the fitting 13 also makes it much easier to remove abrasive dust from the bore 16 by blowing compressed air therethrough than if the lower portion 18 of the bore 16 were provided with an internal thread.

It will be understood that certain changes may be made in the construction or arrangement of the sanding pad structure disclosed herein without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A rotatable sanding pad for supporting an abrasive disc comprising, a generally circular pad member having a generally concave slightly conical undersurface against which an abrasive disc is adapted to be retained, means for retaining a disc against said undersurface, said undersurface of said pad member being provided with a multiplicity of radially extending saw-tooth ribs each being defined by a first radial wall normal to said undersurtace and by a second radial inclined wall, said ribs being adapted to aid in preventing slippage of an abrasive disc retained thereagainst relative to said pad member during operation thereof in an angular direction for advancing said first walls forwardly of said second walls.

2. A rotatable sanding pad for supporting an abrasive disc comprising, a generally circular pad member having an undersurface against which an abrasive disc is adapted to be retained, means for retaining a disc against said undersurface, and a multiplicity of radially extending grooves formed on said undersurface of said pad memher and defining therebetween a multiplicity of radially extending saw-tooth ribs each being defined by a first radial wall normal to said nndersurface and by a second radial inclined Wall, said ribs being adapted to aid in preventing slippage of an abrasive disc retained thereagainst relative to said pad member during operation thereof in an angular direction for advancing said first walls forwardly of said second walls 1 3. A rotatable sanding pad for supporting an abrasive disc comprising, a generally circular pad member formed of a hard rubber-like material and having a generally concave slightly. conical undersurface against which an abrasive disc is adapted to be retained, and a multiplicity of radially extending grooves formed on said undersurface of said pad member and defining therebetween a multiplicity of radially extending flexible saw-tooth ribs each being defined by a first radial Wall normal to said undersurface and by a second radial inclined wall, said ribs being adapted to aid in preventing slippage of an abrasive .disc retained thereagainst relative to said pad member during operation thereof in an angular direction for advancing said first walls forwardly of said second walls, said radial grooves defining said ribs increasing progressively in depth and width toward the outer peripheral edge of said pad member whereby to provide greater rib flexibility at the outer portion of said pad member where the sanding pressure is greatest.

4. A rotatable sanding pad for supporting an abrasive disc comprising, a central fitting adapted to be connected to a rotatable drive member, a generally circular pad member mounted on said fitting and having an undersurface against which an abrasive disc is adapted to be retained, means for retaining an abrasive disc against said undersurface of said pad member, and a multiplicity of radially extending grooves formed in said undersurface of said pad member whereby to define therebetween a multiplicity of radially extending saw-tooth ribs, each being defined by a first radial wall normal to said undersurface and by a second radial inclined Wall, said ribs being adapted to aid in preventing slippage of an abrasive disc retained thereagainst relative to said pad member during operation thereof in an angular direction for advancing said first Walls forwardly of said second walls.

5. A rotatable sanding pad for supporting an abrasive disc comprising, a central fitting adapted to be connected to a rotatable drive member, a generally circular pad member formed of hard rubber-like material molded on said fitting and having a generally concave slightly conical undersurface against which an abrasive disc is adapted to be retained, a multiplicity of radially extending grooves formed in said undersurface of said pad member whereby to define therebetween a multiplicity of radially extending flexible saw-tooth ribs each being defined by a first radial wall normal to said undersurface and by a second radial inclined wall, said ribs being adapted to aid in preventing slippage of an abrasive disc retained thereagainst relative to said pad member during operation thereof in an angular direction for advancing said first walls forwardly of said second walls, said radial grooves defining said ribs increasing progressively in depth and width toward the outer peripheral edge of said pad member whereby to provide greater rib flexibility at the outer portion of said pad member where the sanding pressure is greatest, and releasable mean interengageable with said fitting for retaining an abrasive disc against said un dersurface of said pad member.

6. A rotatable sanding pad for supporting an abrasive disc comprising, a centrally bored fitting adapted to be connected at its upper end to a rotatable drive member, lug means provided in the lower portion of the bore in said fitting, a generally circular pad member mounted on said fitting and having an undersurface against which an abrasive disc is adapted to be fitted, disc retaining means releasably engagable with said lug means in said fitting bore for retaining a centrally bored abrasive disc against said undersurface of said pad member, and a multiplicity of radial grooves formed in said undersurface of said pad member whereby to define therebetween a multiplicity of radially extending saw-tooth ribs each being defined by a first radial wall normal to said undersurface and by a second radial inclined wall, said ribs being adapted to aid in preventing slippage of an abrasive disc retained against the undersurface of said pad member relative to said pad member during operation thereof in an angular direction for advancing said first walls forwardly of said second walls, said radial grooves defining said ribs increaing progressively in depth and width toward the outer peripheral edge of said pad member.

7. A rotatable sanding pad for supporting an abrasive disc comprising, a centrally bored fitting adapted to be connected at its upper end to a rotatable drive member, a pair of diametrically opposite longitudinally spaced lugs projecting radially inwardly of the lower portion of the bore in said fitting, a generally circular pad member formed of hard rubber-like material molded on said fitting and having an undersurface against which an abrasive disc is adapted to be fitted, a disc retainer having an upper externally threaded end portion which is adapted to be rotatably inserted into the lower end of said fitting bore in threading engagement with said pair of lugs therein, said retainer having a radially extending flange portion at its lower end for retaining a centrally bored abrasive disc against said undersurface of said pad member, and a multiplicity of radial grooves formed in said undersurface of said pad member whereby to define therebetween a multiplicity of radially extending flexible saw-tooth ribs each being defined by a first radial Wall normal to said undersurface and by a second radial inclined wall, said ribs being adapted to aid in preventing slippage of an abrasive disc retained against the undersurface of said pad member relative to said pad member during operation thereof in an angular direction for advancing said first walls forwardly of said second walls, and said radial grooves defining said ribs increasing progressively in depth and width toward the outer peripheral edge of said pad member whereby to provide greater rib flexibility at the outer portion of said pad member where the sanding pressure is greatest.

References Cited in the file of this patent UNITED STATES PATENTS 1,214,244 Waltz Jan. 30, 1917 2,114,967 Myers Apr. 19, 1938 2,573,411 DeMichel Oct. 30, 1951 2,767,528 Tocci-Guilbert Oct. 23, 1956 2,902,799 Beck Sept. 8, 1959 2,958,166 Poland Nov. 1, 1960 

2. A ROTATABLE SANDING PAD FOR SUPPORTING AN ABRASIVE DISC COMPRISING, A GENERALLY CIRCULAR PAD MEMBER HAVING AN UNDERSURFACE AGAINST WHICH AN ABRASIVE DISC IS ADAPTED TO BE RETAINED, MEANS FOR RETAINING A DISC AGAINST SAID UNDERSURFACE, AND A MULTIPLICITY OF RADIALLY EXTENDING GROOVES FORMED ON SAID UNDERSURFACE OF SAID PAD MEMBER AND DEFINING THEREBETWEEN A MULTIPLICITY OF RADIALLY EXTENDING SAW-TOOTH RIBS EACH BEING DEFINED BY A FIRST RADIAL WALL NORMAL TO SAID UNDERSURFACE AND BY A SECOND RADIAL INCLINED WALL, SAID RIBS BEING ADAPTED TO AID IN PREVENTING SLIPPAGE OF AN ABRASIVE DISC RETAINED THEREAGAINST RELATIVE TO SAID PAD MEMBER DURING OPERATION THEREOF IN AN ANGULAR DIRECTION FOR ADVANCING SAID FIRST WALLS FORWARDLY OF SAID SECOND WALLS 